someone please school me on gas mileage and o2's please

[redemn93]

so my tahoe has 125k miles on it. i just replaced the plugs with the delco replacement iridiums last night. wires also cause most broke while removing them. i am pretty sure they are the factory plugs. delco calls for a .040 gap and these were worn to .060 (some a little more, some a little less).

i am concerned because i have only gone 150 miles on half a tank. i have been driving it a little hard but nothing that should have eaten gas like that. i also dropped in a K&N and new fuel filter. next week i am going to remove and clean the TB and change the PCV valve. im reading that you guys say a tune helps a good bit with MPG?

now to the point. with 125k miles, should i change the o2's even though i have no CEL? is there a set (front or rear) that affect MPG the most? or just dont mess with it until i get a light?

once i get all the maintanance and small problems fixed i would like to do headers, exhaust, and the airbox mod with a smooth tube to the throttle body. maybe a ported TB and a tune. all in due time. thanks for any help!!

 

[COTahoeLS]

The front o2 effects your gas mileage. The rear one is only used to check cat efficiency (read, doesn't do a damn thing really).

I would recommend possibly replacing the front o2 with new one and then get a tune as you will gain at most 1-2 mpg through the tune alone (read, 25-50 more miles per tank).

-E

 

[redemn93]

these are dual cat trucks right? so there are 2 front o2s. i may do that this weekend. thanks.

 

[COTahoeLS]

Correct!

-E